This invention relates in general to conveyors and in particular to a new and useful scraper device particularly for conveyors used in mining minerals.
The invention particularly concerns a scraper device to clean conveyor belts especially shuttle belt conveyors with a bearing axle placed below the conveyor belt over its width to provide mounting possibilities for spring arms with a mounting device on one end to connect to the bearing axle and scraper blade holders for scraper blades at the other end which are pressed against the lower segment of the conveyor belt.
Scraper devices for cleaning conveyor belts are known in which the rigidly fastened scraper blades fitted to the ends of the spring arms are pressed in an advancing position against the lower segment of the forward moving conveyor belt. Advancing positions with scraper blades that rotate elastically backward and downward and have a rotational axis essentially below the scraper edge is problematic. This is especially because, as a consequence of differing frictional and stripping forces through belt velocity, surface roughness or material sticking or through large material amounts, a socalled stick-slip effect between scraper blade and belt surface occurs resulting in chatter marks and finally belt damage. To avoid these disadvantages and to achieve cleaning with the least amount of damage to the belt, a trailing position for the scraper blades is preferred which rotate with a spring arms to which they are fastened around a rotational axis. With shuttle belt conveyors this trailing position becomes, however, an advancing position with the mentioned disadvantages when the conveyor belt runs in the reverse direction, that is backward, if there is not an additional joint which allows for the return flip of the scraper blade. A further disadvantage of the known scraper devices lies in the fact that the spring arms are regularly fashioned as torsion spring arms, i.e. torsion springs are placed on the mounting device for the bearing axle. In this respect it is a relatively complicated construction method which requires pre-assembly from individual structural units.
A scraper device, finally, is known in which the holder device, the spring arm and the stripping scraper blade consist of wear and tear resistant, elastic and homogeneous polyurethane. The elastic bending of the spring arm creates the pressing force for the scraper blade. A disadvantage of this construction is that it represents a comprise between the wear and tear and the scraping behavior of the spring effect which decreases because of permanent deformation. If the scraper blade is worn out, the entire scraper unit has to be replaced. All known scraper devices have the one disadvantage in common that the angle of pitch of the scraper blade changes continuously as a consequence of wear and tear and changing scraper contour lines and therefore optimum cleaning is never achieved.